There has been increasing interest in the treatment of teeth with fluid polymerizable monomers which are activated to form on the tooth surface, after curing, a strongly adherent protective polymer film coating.
It has generally been the practice to apply these monomeric materials with a brush or spatula to the tooth surface, the polymerizable fluid wetting the surface and tending to flow over the same. Such treatment is awkward at best for the treatment of the upper teeth as the polymerizable monomer, particularly if in a thin fluid state, has a tendency to flow down the applicator making it difficult to apply controlled amounts to the tooth area being treated.
It has heretofore been proposed to use a syringe for applying dental varnishes as shown, for example, in U.S. Pat. No. 2,142,780. However, where the material to be applied has been activated, for example, as the pit and fissure-treating compositions described in U.S. Pat. No. 3,663,501, the activated treating composition remaining in the dispenser would polymerize thus making it necessary to discard the same. As the setting time for such composition, after being activated, is generally in the order of about 5 minutes or less it is apparent that there would not be sufficient time to clean all remaining activated treating composition from a syringe prior to its polymerization.
It has been observed that the best coating of the teeth is obtained when the treating monomer is highly fluid and readily wets the surface of the tooth so as to rapidly flow out over the surface in a thin film. For such treatment it is not only important to carefully position the monomeric coating material on the tooth area to be treated but also to place the coating composition on the tooth in a dropwise maner so that only small quantities are used.
In accordance with the present invention a dispensing applicator is designed which enables the operator to place a drop of activated monomer in a controlled manner on either upper or lower teeth without worry of the activated monomer flowing down the instrument during application. Also, the activated monomer cannot polymerize in the instrument so as to deleteriously effect its operation or reuse. Also, the applicator of the present invention is so designed as to enable the dentist or dental assistant to accurately place a small controlled amount of activated monomer on a tooth surface regardless of its location in the mouth.
The applicator of the present invention is in the form of an elongated member having an applicator head and operating mechanism at one end with the remainder of the elongated member serving as a handle to be grasped by the dentist. A disposable tip, through which the coating composition is applied, is removably carried by the applicator head and projects at an angle with respect to the handle for ease of application.
The applicator head contains a semi-spherical chamber which opens into a relatively short longitudinal first bore contained in the handle portion immediately adjacent to the applicator head. A simultaneously shaped member, such as a cupped resilient diaphram, is positioned in the chamber the diaphram being of such size and shape that its outer surface is adjacent to and preferably contacts the inner surface of the semi-circular chamber.
A closure member positioned on the end of the applicator serves to close the base portion of this first semi-spherical chamber and hold and seal the outer edge of the resilient member. The closure contains a smaller second chamber which is in direct alignment with the longitudinal bore contained in the handle and contains a second bore of somewhat smaller diameter which extends at an angle to the longitudinal axis of the applicator. This second bore extends through the cover and is in direct communication with the second chamber. This second bore contained in the closure member is adapted to receive a disposable tube which is the applicator tip into which treating compositions are drawn and from which applied to the teeth.
The first bore, which is located in the handle portion adjacent applicator head, contains a piston which is adapted to move longitudinally within this first bore and press against the resilient member for compressing the same. An angular-operating lever is pivotally secured on top of the applicator with one leg of the lever extending rearwardly on top of the applicator and essentially paralleling the same with the other leg of the lever extending into the first bore of the applicator and adapted to press on one end of the piston for actuating the same.
When the applicator is to be used, a disposable tube is inserted into the end of the second bore in the applicator head. Pressure is then applied on the exposed leg of the angular-operating lever. This causes the piston to be pushed forward where it presses against the resilient member and expresses air from the semi-spherical chamber. The applicator is then immersed in the activated monomer with which the tooth is to be treated and pressure on the exposed leg of the lever is released. The semi-spherical resilient diaphram then retains its initial form with the result that a partial vacuum is created and air is drawn into the semi-spherical chamber and the liquid up into the disposable tube. The size of the semi-spherical chamber, the distance of movement of the piston, and the diameter and length of the disposable tube are related to each other so that the change in volume in the semi-spherical chamber on movement of the piston is such that only a few drops of liquid are drawn into the disposable tube the amount never being such that the disposable tube will fill and liquid flow into the second chamber inside the closure.